Apr 18, 2026 10:16 PM
https://www.eurekalert.org/news-releases/1124758
INTRO: In a converted 2013 Toyota Sienna affixed with a hand-built telescopic weather device protruding from the roof, Penn State experts in meteorology and atmospheric science made their way down the nation’s eastern coast in June 2024 in search of Florida’s famed near-daily summer thunderstorms.
They were hoping to catch corona discharges, a long-hypothesized atmospheric weather phenomenon where miniscule pulses of electricity dance at the tips of tree leaves, causing the canopy to glow in the ultraviolet (UV). For more than 70 years, scientists have suspected treetops might emit these corona electrical discharges because of odd electric field activity in and over forests during storms, yet they have never been documented outside the lab.
The team, consisting of William Brune, distinguished professor of meteorology and atmospheric science; Patrick McFarland, a doctoral candidate in meteorology and atmospheric science; Jena Jenkins, assistant research professor; and David Miller, a former associate research professor who is now at the Penn State Applied Research Lab; worked to be the first to document this effect.
They chose the Sunshine State because of its propensity to produce frequent thunderstorms. However, as is often the case during research endeavors, the typical weather proved atypical. For three weeks in Florida, McFarland and Brune chased pop-up storms that left as quickly as they formed.
The researchers had little to show for their efforts until, as they made their way back to Penn State, massive and sustained storms began cropping up just west of Interstate 95. The team caught an exit, nestled in a parking lot at the University of North Carolina at Pembroke, and trained their instruments to the top branches of a sweetgum tree that the rangefinder logged as 100 feet from their van.
The thunderstorm flashed lightning and poured rain for nearly two hours, giving them time to also observe corona on a nearby long needle loblolly pine tree as the storm waned. The results, which were the first directly-observed corona discharges occurring in nature, were recently published in Geophysical Research Letters.
“This just goes to show that there’s still discovery science being done,” said McFarland, lead author on the paper. “For more than half a century, scientists have theorized that corona exists, but this proves it.”
Corona discharges take shape during storms, the researchers said, because clouds build up strong negative charges that attract the opposite positive charge on the ground below. Opposites attract and this positive electrical ground charge rises up through the trees to the highest point, causing an electric field on the tiny, hair-like tips of leaves that is great enough to create the weak corona glow in both visible and UV form. This UV from the corona breaks apart water vapor, producing hydroxyl.
Hydroxyl is the atmosphere’s main oxidizer. Oxidizers clean the air by reacting with chemicals emitted into the air, making other chemicals that are easier to remove. These chemicals include volatile organic compounds emitted by trees or human activities and the greenhouse gas methane. The team’s prior research found corona discharges to be a substantial source of atmospheric cleansers in the forest canopy... (MORE - no ads)
INTRO: In a converted 2013 Toyota Sienna affixed with a hand-built telescopic weather device protruding from the roof, Penn State experts in meteorology and atmospheric science made their way down the nation’s eastern coast in June 2024 in search of Florida’s famed near-daily summer thunderstorms.
They were hoping to catch corona discharges, a long-hypothesized atmospheric weather phenomenon where miniscule pulses of electricity dance at the tips of tree leaves, causing the canopy to glow in the ultraviolet (UV). For more than 70 years, scientists have suspected treetops might emit these corona electrical discharges because of odd electric field activity in and over forests during storms, yet they have never been documented outside the lab.
The team, consisting of William Brune, distinguished professor of meteorology and atmospheric science; Patrick McFarland, a doctoral candidate in meteorology and atmospheric science; Jena Jenkins, assistant research professor; and David Miller, a former associate research professor who is now at the Penn State Applied Research Lab; worked to be the first to document this effect.
They chose the Sunshine State because of its propensity to produce frequent thunderstorms. However, as is often the case during research endeavors, the typical weather proved atypical. For three weeks in Florida, McFarland and Brune chased pop-up storms that left as quickly as they formed.
The researchers had little to show for their efforts until, as they made their way back to Penn State, massive and sustained storms began cropping up just west of Interstate 95. The team caught an exit, nestled in a parking lot at the University of North Carolina at Pembroke, and trained their instruments to the top branches of a sweetgum tree that the rangefinder logged as 100 feet from their van.
The thunderstorm flashed lightning and poured rain for nearly two hours, giving them time to also observe corona on a nearby long needle loblolly pine tree as the storm waned. The results, which were the first directly-observed corona discharges occurring in nature, were recently published in Geophysical Research Letters.
“This just goes to show that there’s still discovery science being done,” said McFarland, lead author on the paper. “For more than half a century, scientists have theorized that corona exists, but this proves it.”
Corona discharges take shape during storms, the researchers said, because clouds build up strong negative charges that attract the opposite positive charge on the ground below. Opposites attract and this positive electrical ground charge rises up through the trees to the highest point, causing an electric field on the tiny, hair-like tips of leaves that is great enough to create the weak corona glow in both visible and UV form. This UV from the corona breaks apart water vapor, producing hydroxyl.
Hydroxyl is the atmosphere’s main oxidizer. Oxidizers clean the air by reacting with chemicals emitted into the air, making other chemicals that are easier to remove. These chemicals include volatile organic compounds emitted by trees or human activities and the greenhouse gas methane. The team’s prior research found corona discharges to be a substantial source of atmospheric cleansers in the forest canopy... (MORE - no ads)